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1984 (1)
1Author    Lothar Grün, MartinG. PeterRequires cookie*
 Title    Incorporation of Radiolabeled Tyrosine, N-Acetyldopamine, N-/J-Alanyldopamine, and the Arylphorin Manducin into the Sclerotized Cuticle of Tobacco Hornworm (Manduca sexta) Pupae  
 Abstract    Radiolabeled manducin, which is the arylphorin (i.e. tyrosine-rich larval serum protein) o f the tobacco hornworm Manduca sexta was prepared by in vivo biosynthesis from [U -l4C]-L-tyrosine. In order to see whether manducin is incorporated into the cuticle o f d evelop in g pupae and participates in cuticle sclerotization, the radiolabeled protein was injected into late last larval instar larvae. Fractionation o f the sclerotized pupal cuticle into a buffer soluble, acid soluble and acid insoluble fraction shows that up to 2.6% o f peptidic tyrosine residues end up in the acid soluble portion. Another 0.5% are recovered from the acid insoluble fraction by com bustion. Only 30% o f peptidic tyrosine residues o f m anducin incorporated into the acid soluble fraction are recovered as tyrosine. The presence o f radioactivity in the acid insoluble fraction suggests that peptidic tyrosine residues are transformed partly into m elanin-like m aterial. The in­ corporation o f manducin into the cuticle o f pupae is also evident from im m unological studies. Relative large quantities o f radiolabeled acid insoluble m elanine like m aterial is also recovered from sclerotized cuticle after incorporation o f radiolabeled tyrosine as well as tanning substrates N-acetyldopam ine and N-/?-alanyldopamine. A p plication o f doubly labeled [7-3H,8-l4C]-N-acetyldopamine shows a high loss o f 3H in the acid insoluble fraction. It is suggested that tanning agents form lignine-like polymers and that sclerotization results from copolym erization with peptidic tyrosine residues in the cuticle. Thus, the arylphorin m anducin appears to be an important constituent o f the sclerotization system in M anduca sexta. 
  Reference    Z. Naturforsch. 39c, 1066—1074 (1984); received June 1/August 27 1984 
  Published    1984 
  Keywords    Arylphorins, Copolymerization, Insect Cuticle, Sclerotization, Tanning Substrates 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-1066.pdf 
 Identifier    ZNC-1984-39c-1066 
 Volume    39